Glass cutting machine, glass cutter, and glass cutting method

ABSTRACT

A glass cutter is provided which can form, using a wheel, a uniform crack in glass even when a projection or an earlier-formed scribe line is present on the glass. When the wheel is moved on the glass, a fracture layer is formed causing a rib mark to be formed below the fracture layer and a crack to be formed below the rib mark. To cut the glass, the crack is required to be formed uniformly. Applying a force to resist the rotating force of the wheel makes it possible to form a uniform crack even when a projection is present on the glass. This improves glass cutting yield.

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent ApplicationJP 2010-142876 filed on Jun. 23, 2010, the content of which is herebyincorporated by reference into this application.

FIELD OF THE INVENTION

The present invention relates to technology which, when separating, forexample, liquid crystal display (LCD) panels from a mother substrate byscribing, enables vertical cracks to be formed stably to achieve stablescribing.

BACKGROUND OF THE INVENTION

In LCD panel production, to improve production efficiency, plural LCDpanels are formed on a large mother panel, then they are separated fromthe mother panel by scribing. Generally, for glass cutting, a wheel madeof, for example, sintered diamond or cemented carbide with a diameter ofseveral millimeters is used. The wheel has a circumferential edge and ismoved on a glass surface while applying a certain pressure to the glasssurface. The wheel moves on the glass surface cutting into the glass byseveral micrometers thereby forming a linear score measuring severalmicrometers both in depth and in width. Such a linear score mayhereinafter be referred to as a “fracture layer.”

At the same time as the linear score is formed, a crack with a depthvertical to the glass surface of several tens of micrometers to severalhundred micrometers is formed immediately below the linear score. Theformation of such a vertical crack propagates, as the wheel advances,ahead of the advancing wheel position with a front angle of severaldegrees with respect to the vertical direction extending right below thewheel. That the formation of the vertical crack propagates with such anangle can be known by observing a mark called a rib mark which isgenerated on the cut surface of the glass. The depth of the verticalcrack is the depth of the rib mark plus the depth of a crack formed tofurther extend depthwise beyond the rib mark. As far as the presentinvention is concerned, the rib mark depth and the depth of the verticalcrack may be regarded, for the sake of convenience, as being identical.Generally, the operation and what is caused by the operation describedabove are collectively referred to as scribing. To separate a sheet ofglass into multiple parts, one side of a sheet of glass is scribed, andthe scribed portion is pressed from the other side causing the verticalcrack formed in the scribed portion to extend deeper. This glassseparation may be referred to as breaking.

FIG. 22 shows a glass cutter 1. As shown, the glass cutter 1 includes awheel 10 used for scribing, a wheel pin 11 serving as a shaft of thewheel 10, and a holder 12 supporting the wheel 10 and the wheel pin 11.

FIG. 23 is a sectional view of the wheel 10 used for scribing. Referringto FIG. 23, the wheel 10 has a ridge, i.e. a cutting edge 101, bevels102, and sides 103. The wheel 10 has thickness t ranging from 0.5 to 1.0mm, edge angle θ ranging from 100 to 130 degrees, and diameter d rangingfrom 2 to 3 mm. The wheel 10 is formed of, for example, sintered diamondor cemented carbide.

FIGS. 24A and 24B are a plan view and a sectional view, respectively,showing scribing of glass performed using the wheel 10 shown in FIG. 23.Referring to FIG. 24A, a fracture layer 201 formed by the wheel 10 haswidth w which is about several micrometers.

Referring to FIG. 24B, the fracture layer 201 formed by the wheel 10 hasdepth d1, and a rib mark 202 is formed below the fracture layer 201 witha crack 203 further extending from the rib mark 202. Depth d1 of thefracture layer 201 is several micrometers. Depth d2 from the glasssurface to the bottom of the crack ranges from several tens ofmicrometers to several hundred micrometers.

In FIG. 24B, a white arrow MD denotes the moving direction of the wheel10, “FF” denotes a force moving the wheel 10, and “RF” denotes arotating force generated as the wheel 10 moves. Also, “F1” denotes aforce the wheel 10 applies, in its moving direction, to the glass 300;“F2” denotes a force the wheel 10 vertically applies to the glass 300;and “F3” denotes a resultant force of F1 and F2. As the wheel 10 moves,while rotating, in the direction MD, the crack 203 is formed in theglass 300.

The above glass cutting mechanism is described, for example, inliterature by Toshihiko Ono and Yuko Ishida, “Cuttability of AMLCD GlassSubstrate” in SID 02 DIGEST, pages 45-47 (2002) and also in literatureby T. Murata, S. Miwa, H. Yamazaki, S. Yamamoto, “Suitable ScribingConditions for AMLCD Glass Substrate” in SID Digest, pages 374-377.Also, a configuration for stably forming a crack when forming a scribeline crossing an existing scribe line on a glass surface is described,for example, in Japanese Patent Laid-Open No. 2009-93051. Furthermore, awheel 10 with notches formed on its cutting edge so that it may securelyrotate on the glass surface is described in WO2007/004700. Stillfurthermore, a configuration in which a wheel 10 and a rotary shaft forrotating the wheel 10 are united is described in Japanese PatentLaid-Open No. 2001-246616.

SUMMARY OF THE INVENTION

FIGS. 25A to 25D show operation of the wheel 10 in a case where amicroprojection (hereinafter also referred to simply as a “projection”)301 is present on the surface of the glass 300. FIG. 25A shows the wheel10 moving on a flat surface portion of the glass 300. In FIG. 25B, thewheel 10 is shown having ridden on the projection 301 present on theglass 300. In the state shown in FIG. 25B with the wheel 10 over theprojection 301, the wheel 10 applies, in its moving direction, no forceto the glass 300. In this state, the force applied from the wheel 10 tothe glass 300 is F2 only. As a result, formation of the crack 203 thathas been continued until before the wheel 10 has ridden on theprojection 301 is once discontinued.

FIG. 25C shows the wheel 10 that is, having passed the projection 301,about to start moving on a flat surface portion of the glass 300 again.As shown in FIG. 25C, the wheel 10, after passing the projection 301,starts applying forces F1, F2, and F3 to the glass 300 again to causeformation of the crack 203 to be resumed. FIG. 25D shows a state inwhich the wheel 10 passed the projection 301 and the crack 203 is formedin the glass 300 in a normal manner.

FIGS. 25C and 25D show that no crack 203 is formed in portion Y belowthe projection 301 present on the glass surface. Thus, with the glass300 having a portion where the crack 203 required for subsequent glassbreaking operation is not formed, there is a large risk that the portioncauses, by preventing the glass 300 from being stably broken into pluralparts, generation of defective parts in the subsequent glass breakingoperation. This problem cannot be adequately dealt with by theconfigurations described in Japanese Patent Laid-Open No. 2009-93051 andWO2007/004700.

In many cases of LCD cell cutting, particularly, where plural LCD cellsare cut out from a single LCD sheet, first, plural first scribe linesare formed on the LCD sheet, then plural second scribe lines are formedperpendicularly to the first scribe lines, so that the first scribelines and the second scribe lines have intersections where they cross.

When a second scribe line is formed using a wheel 10 to cross a firstscribe line already formed, formation of a vertical crack along thesecond scribe line to propagate ahead of the position of the wheel 10may be once discontinued at the intersection of the first and secondscribe lines, requiring the wheel 10 to move several hundred micrometerspast the intersection before the vertical crack formation can beresumed. Namely, the vertical crack formed along the second scribe lineis not formed over a range of several hundred micrometers from theintersection. Such a scribe line intersection with no vertical crackformed along the second scribe line makes glass breaking difficult andpossibly causes glass edge chipping in the subsequent glass breakingoperation. Such discontinuation of vertical crack formation is referredto as “intersection skipping.” Intersection skipping is assumed to occurwhen formation of a vertical crack propagating ahead of the position ofthe wheel 10 is discontinued at a scribe line intersection causing thewheel 10 to temporarily ride on the glass surface thereby preventingformation of a fracture layer and, hence, preventing formation of avertical crack.

The above process is schematically illustrated in FIGS. 26A to 26D. FIG.26A shows the wheel 10 moving, while rotating, toward an existing scribeline 302. The crack 203 is formed in the glass 300 in the manner asdescribed above with reference to FIGS. 25A to 25D. FIG. 26B shows astate in which formation of the crack 203 by the wheel 10 has beendiscontinued by the presence of the scribe line 302.

Namely, when the wheel 10 passes the scribe line 302, it enters a statesimilar to riding on a new glass edge. In such a state, F2 is the onlyforce applied from the wheel 10 to the glass 300 with no force appliedto the glass 300 in the moving direction of the wheel 10. As a result,formation of the crack 203 in the glass 300 is discontinued.

FIG. 26C shows a state in which, with the wheel 10 having crossed thescribe line 302, formation of a vertical crack in the glass 300 is beingresumed. FIG. 26D shows a state in which the wheel 10 passed the scribeline 302 and the crack 203 is formed in the glass 300 in a normalmanner.

FIGS. 26C and 26D show that no crack 203 is formed in portion Z, i.e. inthe vicinity of the scribe line 302. Thus, with the glass 300 having aportion where the crack 203 required for subsequent glass breakingoperation is not formed, there is a large risk that the portion causes,by preventing the glass 300 from being stably broken into plural parts,generation of defective parts in the subsequent glass breakingoperation. This problem cannot be adequately dealt with by theconfigurations described in Japanese Patent Laid-Open No. 2009-93051 andin WO2007/004700.

An object of the present invention is to enable continuous formation ofa crack and stable scribing by the wheel 10 so as to improve the yieldin the process of breaking a mother substrate into plural LCD panelseven in cases where there is a microprojection on the glass surface orthere is a scribe line already formed on the glass surface.

According to the present invention made in view of the above problem,when moving a wheel on a glass surface while rotating the wheel, a forceto oppose, as if braking, the wheel rotation is applied. This makes itpossible to stably form a vertical crack on the glass surface even incases where a microprojection is present on the glass surface.Furthermore, it is also made possible to inhibit intersection skippingwhich causes the crack formation to be discontinued when the wheel movescrossing an earlier-formed scribe line.

In other words, it is a principle of the present invention to restraingeneration, due to rotation of a wheel, of an upward force by applying,to the wheel, a force to oppose the rotation of the wheel. Namely, thewheel is prevented from riding on a glass surface even when the glasssurface includes projections, depressions, or otherwise non-flatportions or even when the wheel moves crossing an earlier-formed scribeline. In this way, it is easier for the wheel to keep applying a force,in its moving direction, to the glass in a stable manner so as to stablycontinue scribing.

According to the present invention, in glass cutting operation, a wheelmoving on a glass surface does not ride on the glass surface even whenmicrodepressions and microprojections are present on the glass surface.Also, the wheel is prevented from riding on the glass surface when itfinishes crossing an earlier-formed scribe line. This can preventvertical crack formation in the glass from becoming unstable or frombeing discontinued.

Since, in a process to scribe a mother substrate and separate LCD panelsfrom the mother substrate, scribe lines can be continuously and stablyformed, the yield of the scribe and break process can be improved. Sincesuch a scribe and break process for separating display panels from amother substrate is also used to manufacture organic EL display panels,the present invention can also be effectively applied to the manufactureof organic EL display panels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1D are schematic diagrams illustrating the principle of thepresent invention;

FIGS. 2A to 2D are schematic diagrams illustrating the principle of thepresent invention;

FIG. 3 is a diagram illustrating a first embodiment of the presentinvention;

FIG. 4 is a diagram illustrating a second embodiment of the presentinvention;

FIG. 5 is a diagram illustrating a third embodiment of the presentinvention;

FIG. 6 is a diagram illustrating a fourth embodiment of the presentinvention;

FIG. 7 is a diagram illustrating a fifth embodiment of the presentinvention;

FIG. 8 is a diagram illustrating a sixth embodiment of the presentinvention;

FIG. 9 is a diagram illustrating a seventh embodiment of the presentinvention;

FIG. 10 is a diagram illustrating an eighth embodiment of the presentinvention;

FIG. 11 is a diagram illustrating a ninth embodiment of the presentinvention;

FIG. 12 is a diagram illustrating a tenth embodiment of the presentinvention;

FIG. 13 is a diagram illustrating an eleventh embodiment of the presentinvention;

FIG. 14 is a diagram illustrating a twelfth embodiment of the presentinvention;

FIG. 15 is a diagram illustrating a thirteenth embodiment of the presentinvention;

FIG. 16 is a diagram illustrating a fourteenth embodiment of the presentinvention;

FIG. 17 is a diagram illustrating a fifteenth embodiment of the presentinvention;

FIG. 18 is a diagram illustrating a sixteenth embodiment of the presentinvention;

FIG. 19 is a diagram illustrating a seventeenth embodiment of thepresent invention;

FIG. 20 is a diagram illustrating an eighteenth embodiment of thepresent invention;

FIG. 21 is a diagram illustrating a nineteenth embodiment of the presentinvention;

FIG. 22 is a diagram illustrating an existing glass cutter;

FIG. 23 is a sectional view of a wheel 10;

FIGS. 24A and 24B are diagrams illustrating scribing by the wheel 10;

FIG. 25A to 25D are diagrams illustrating a problem with scribingperformed using prior-art technology; and

FIG. 26A to 26D are diagrams illustrating another problem with scribingperformed using prior-art technology.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1A to 1D are schematic diagrams illustrating the principle of thepresent invention based on an example case in which a wheel 10 movesacross a microprojection 301 present on a glass 300. For FIGS. 1A to 1D,description already provided in the foregoing with reference to FIGS.25A to 25D and other drawings will be omitted. Referring to FIG. 1Ashowing the wheel 10 moving toward the projection 301 present on theglass surface, the wheel 10, when moving in the direction denoted by awhite arrow MD, rotates with a rotating force RF. According to thepresent invention, a force RRF to oppose the rotating force RF isapplied. Mechanisms used to generate the force RRF will be described inconnection with the following embodiments. Namely, the present inventionprovides a configuration for braking the rotation of the wheel 10.

FIG. 1B shows the wheel 10 passing the projection 301 on the glasssurface. With the force to oppose the rotation of the wheel 10 applied,the wheel 10 is prevented from riding on the projection 301. As aresult, the wheel 10 is allowed to form the fracture layer 201 evenwhere the projection 301 is present, so that the crack 203 is formed tobe continuous in the glass 300. With the force RRF to oppose rotation ofthe wheel 10 applied, the wheel 10 cannot easily rotate where theprojection 301 is present, so that the wheel 10 is caused to pass theprojection 301 sliding without riding thereon. This allows the wheel 10to continue formation of the crack 203. Note that, for the sake ofsimplification, the projection 301 on the glass surface is not shown inFIG. 1B.

FIG. 10 shows a state in which the wheel 10 has passed the projection301. In FIG. 10, it is shown that a crack is formed also in portion Wbelow the projection 301 of the glass. FIG. 1D shows a state in whichthe wheel 10 having passed the projection 301 is moving in the directionof arrow MD. As shown in FIG. 1D, even though the projection 301 ispresent on the glass surface, the crack 203 is continuously formed inthe glass by the wheel 10.

FIGS. 2A to 2D schematically show the wheel 10 moving across an existingscribe line 302. For FIGS. 2A to 2D, description already provided in theforegoing with reference to FIGS. 26A to 26D and other drawings will beomitted. Referring to FIG. 2A showing the wheel 10 moving toward thescribe line 302, a force RRF to oppose a rotating force RF of the wheel10 is applied like in the case shown in FIGS. 1A to 1D.

Referring to FIG. 2B, when the wheel 10 reaches the scribe line 302, acrack 203 formed by the wheel 10 is discontinued. FIG. 2C shows that,immediately after the wheel 10 passes the scribe line 302, formation ofa crack starts. Namely, with the force RRF to oppose rotation of thewheel 10 applied, the wheel 10 does not ride on the surface of the glass300 even when crossing the scribe line 302, so that it can continuouslyform a fracture layer 201, a rib mark 202, and a crack 203.

FIG. 2D shows the wheel 10 further moving in the direction of arrow MDafter crossing the scribe line 302. FIGS. 2C and 2D show that formationof the fracture layer 201, rib mark 202 and crack 203 is started inportion X immediately after the wheel 10 passes the scribe line.

As described above, according to the present invention, the crack 203can be formed in a stable manner even when the wheel 10 passes theprojection 301 present on the glass surface or the existing scribe line302. Thus, plural parts such as LCD panels can be separated from amother substrate in a stable manner. The effects similar to thosedescribed above can also be obtained by applying the present inventionto cases in which organic EL display panels are separated from a mothersubstrate.

The concrete configuration of the present invention will be described inthe following based on embodiments. For each embodiment, a glass cutter1 according to the present invention will be described. Each embodimentprovides a configuration for generating a force to oppose rotation of awheel 10 included in the glass cutter 1.

First Embodiment

FIG. 3 shows the glass cutter 1 of the first embodiment. As shown, thewheel 10 is supported by a wheel pin 11 and the wheel pin 11 issupported by a holder 12. The wheel 10 is formed of sintered diamondadded to by Co which is a magnetic material, so that the wheel 10 as awhole is a magnetic body. The holder 12 is formed of tool steel which isan ultrahard material, so that it is a magnetic body. Two magnets 20 areprovided on outsides of the holder 12. The magnets 20 generate amagnetic field of a prescribed magnetic flux density and, by having themagnetic field crossed by the wheel 10, applies a force to press thewheel 10 against a side of the holder 12. Pressing the wheel 10 againsta side of the holder 12 generates a force RRF to oppose the rotatingforce RF of the wheel 10, so that a fracture layer and a crack can beformed in the glass in a stable manner.

Referring to FIG. 3, the magnets 20 sandwiching the holder 12 aredisposed with the north pole of one of them facing the south pole of theother. According to the present embodiment, the magnets 20 each have adiameter of about 4 mm and a thickness of about 5 to 7 mm. The magnets20 are most preferably made of neodymium-family material which ismechanically strong. Besides neodymium magnets, samarium-cobalt magnetswhich can generate strong magnetic fields may also be used as themagnets 20.

As shown in FIG. 3, the magnets 20 and the wheel 10 are not concentric.Therefore, when the wheel 10 rotates, it crosses a magnetic field withan uneven magnetic flux density. The wheel 10 containing a Co additiveis conductive. When, in this configuration, the wheel 10 rotates, aneddy current is generated in the wheel 10. The eddy current generates aforce to oppose rotation of the wheel 10. This results in allowing thewheel 10 to form a fracture layer and a crack in the glass in a stablemanner. Thus, the wheel 10 can perform scribing in a stable manner.

Second Embodiment

FIG. 4 is a diagram showing a second embodiment of the presentinvention. The wheel 10, wheel pin 11, holder 12, and magnets 20 shownin FIG. 4 are basically identical with those shown in FIG. 3. In theconfiguration shown in FIG. 4, the holder 12 and the magnets 20 aresurrounded by a magnetic frame 21 with a high magnetic permeability withthe magnetic frame 21 providing magnetic paths. In FIG. 4, broken-linearrows shown on the magnetic frame 21 represent a magnetic flux. Withmagnetic paths formed in the magnetic frame 21, reluctance is reduced,so that the magnetic flux to flow through the wheel 10 becomes larger.This increases the force to oppose rotation of the wheel 10.

Since the magnetic flux passing through the wheel 10 becomes larger, theeddy current generated by the rotation of the wheel 10 becomes larger,so that the force generated by the eddy current to oppose rotation ofthe wheel 10 also becomes larger. The magnetic frame 21 is made of, forexample, permalloy which has a high magnetic permeability. The magneticframe 21 is, for example, squarely shaped measuring 15 mm in length ofeach side and 1 mm by 4 to 5 mm in cross-sectional area.

Third Embodiment

FIG. 5 is a diagram showing a third embodiment of the present invention.As shown in FIG. 5, the magnets 20 are embedded in a gap inside theholder 12. The magnets 20 of the third embodiment each measure 3 mm indiameter and 1.5 mm in thickness. Even though, the magnets 20 of thethird embodiment are smaller than those of the first and secondembodiments, the magnets 20 are disposed closer to the wheel 10 in thethird embodiment than in the first and second embodiments, so that amagnetic flux required to be crossed by the wheel 10 can be secured.Referring to FIG. 5, the magnetic poles of the magnets 20 are arrangedalong the thickness direction of the holder 12 with the north and southpoles oriented identically between the two magnets. This secures amagnetic flux perpendicular to the side surfaces of the wheel 10.

In the present embodiment, too, a force to press the wheel 10 againstthe holder 12 so as to oppose rotation of the wheel 10 can be generatedby a magnetic field. As shown in FIG. 5, the magnetic flux isconcentrated in an upper portion of the wheel 10, so that the magneticflux crossing the wheel 10 is uneven. Therefore, rotation of the wheel10 generates an eddy current which also generates a force to opposerotation of the wheel 10.

Fourth Embodiment

FIG. 6 is a diagram showing a fourth embodiment of the presentinvention. As shown in FIG. 6, the holder 12 is divided in two partswith each part holding an embedded magnet 20. Namely, at least a portionof the region between the two holder parts includes the magnets 20. Theholder 12 need not necessarily include plural magnets, it may includeonly one magnet. When plural magnets 20 are used, they are arranged suchthat, between them, unlike poles mutually face. A force to press thewheel 10 against the holder 12 is generated by supplying a leakage fluxfrom the magnets 20 to the wheel 10.

In the above configuration, the holder 12 formed of tool steel which isa magnetic material allows a prescribed amount of magnetic flux to passtherethrough. Referring to FIG. 6, in the region not occupied by themagnets 20 between the two holder parts, a nonmagnetic spacer 25 isfitted. The nonmagnetic spacer 25 is, for example, about 1 mm thick. Thepresence of the nonmagnetic spacer 25 increases the amount of themagnetic flux reaching the wheel 10 so as to press the wheel 10 againstthe holder 12 by a larger force. Thus, a force to oppose rotation of thewheel 10 can be generated.

In the present embodiment, too, the flux to pass through the wheel 10 isuneven. Therefore, rotation of the wheel 10 generates an eddy currentwhich also generates a force to oppose rotation of the wheel 10.

Fifth Embodiment

FIG. 7 is a diagram showing a fifth embodiment of the present invention.As shown in FIG. 7, the magnets 20 are partly embedded in the holder 12with their unlike poles facing each other. By being partly embedded inthe holder 12, the magnets 20 are positioned closer to the wheel 10, sothat the amount of the magnetic flux to pass through the wheel 10 isincreased. This makes the force generated by the magnetic field to pressthe wheel 10 against the holder 12 larger, so that the force to opposerotation of the wheel 10 becomes larger.

In the present embodiment, too, the flux to pass through the wheel 10 isuneven. Therefore, rotation of the wheel 10 generates an eddy currentwhich also generates a force to oppose rotation of the wheel 10.

Sixth Embodiment

FIG. 8 is a diagram showing a sixth embodiment of the present invention.As shown in FIG. 8, the magnets 20 are each disposed on a tilted surface121 of the holder 12. The two magnets 20 are arranged in parallel withtheir magnetic poles oriented identically. According to theconfiguration of the present embodiment, the magnets 20 can be disposedclosely to the wheel 10 using the holder 12 as it is without anymodification, so that a desired magnetic flux can be easily made to passthrough the wheel 10. Hence, a force to oppose rotation of the wheel 10can be easily generated. In the present embodiment, too, a force tooppose rotation of the wheel 10 can also be generated by an eddycurrent.

Seventh Embodiment

FIG. 9 is a diagram showing a seventh embodiment of the presentinvention. As shown in FIG. 9, the magnets 20 are embedded in the holder12. The two magnets 20 are arranged in parallel with their unlike polesfacing each other. In the present embodiment unlike in the first tosixth embodiments, the portion where the magnets 20 are embedded of theholder 12 is smaller in width than the other portion thereof. Thisallows a magnetic flux from the magnets 20 to pass through the wheel 10efficiently. Hence, a force to press the wheel 10 against the holder 12so as to oppose rotation of the wheel 10 can be generated efficiently.In the present embodiment, too, a force to oppose rotation of the wheel10 can also be generated by an eddy current.

Eighth Embodiment

FIG. 10 is a diagram showing an eighth embodiment of the presentinvention. In the eighth embodiment unlike in the first to seventhembodiments, a magnetic flux to pass through the wheel 10 is generatedusing an electromagnet. As shown in FIG. 10, the holder 12 is wound witha coil 30. A required magnetic flux can be made to pass through thewheel 10 by applying an appropriate electric current to the coil 30.Like in the first to seventh embodiments, the magnetic flux generates aforce to press the wheel 10 against the holder 12 so as to opposerotation of the wheel 10.

Referring to FIG. 10, with a current applied to the coil 30, the holder12 serves as a horseshoe-shaped magnet. According to the presentembodiment, a required magnetic flux is generated by the electromagnet,so that the magnetic flux can be controlled easily. Hence, the glasscutter 1 can be used to scribe various kinds of mother substrates.

Ninth Embodiment

FIG. 11 is a diagram showing a ninth embodiment of the presentinvention. Referring to FIG. 11, a fabric member 43 is embedded insidethe holder 12. The fabric member 43 serves as a brake by pressing thebevels 102 of the wheel 10. The fabric member 43 thus generates a forceto oppose rotation of the wheel 10, so that the wheel 10 can performscribing in a stable manner.

Referring to FIG. 11, inside the holder 12, movement of the fabricmember 43 is restrained by a holding pin 431. The fabric member 43 maybe made of, for example, nonwoven fabric like cotton.

Tenth Embodiment

FIG. 12 is a diagram showing a tenth embodiment of the presentinvention. Referring to FIG. 12, a plate spring 41 is disposed insidethe holder 12. The plate spring 41 serves as a brake by pressing thebevels 102 of the wheel 10. The plate spring 41 thus generates a forceto oppose rotation of the wheel 10, so that the wheel 10 can performscribing in a stable manner.

Referring to FIG. 12, the plate spring 41 is bent at a support pin 432.The support pin 432 may be made unnecessary by appropriately changingthe shape of the plate spring 41. The plate spring 41 may be formed of,for example, stainless steel. The plate spring 41 presses the bevels 102of the wheel 10, so that the cutting edge 101 of the wheel 10 is notdamaged. A different material, for example, resin may be interposedbetween the plate spring 41 and the bevels 102 of the wheel 10.

Eleventh Embodiment

FIG. 13 is a diagram showing an eleventh embodiment of the presentinvention. Referring to FIG. 13, washers 42 are disposed between thewheel 10 and the holder 12. The washers 42 press the sides of the wheel10 to serve as brakes. Namely, the friction between each of the washers42 and the wheel 10 generates a force to oppose rotation of the wheel10, so that the wheel 10 can perform scribing in a stable manner.

Each of the washers 42 is doughnut-shaped and measures, for example, 2mm in outer diameter, 1 mm in inner diameter, and 5 to 10 micrometers inthickness. It may be made of either plastic or metal.

Twelfth Embodiment

FIG. 14 is a diagram showing a twelfth embodiment of the presentinvention. Referring to FIG. 14, an elastic spacer 50 is sandwichedbetween the two holder parts. The holder 12 is formed by clamping thetwo holder parts, sandwiching the elastic spacer 50, with a clampingscrew 122.

The wheel 10 is disposed below the holder 12. In the configuration shownin FIG. 14, clamping the two holder parts with the screw 122 causes thewheel 10 to be clamped by the holder 12. Namely, a force to opposerotation of the wheel 10 is generated by clamping the screw 122.

The presence of the elastic spacer 50 between the two parts of theholder 12 makes it possible to adjust the clamping force applied by theholder 12 to the wheel 10. According to the present embodiment, a forceto oppose rotation of the wheel 10 is generated to allow the wheel 10 toperform scribing in a stable manner and the force to oppose rotation ofthe wheel 10 can be arbitrarily controlled.

Thirteenth Embodiment

FIG. 15 is a diagram showing a thirteenth embodiment of the presentinvention. Referring to FIG. 15, a rigid external member 55 is disposedoutside the holder 12 with a spring member 52 disposed between the rigidexternal member 55 and the holder 12 on each side. The spring force ofeach of the spring members 52 causes the holder 12 to undergo elasticdeformation causing the wheel 10 to be pressed by the holder 12. Thisbrakes rotation of the wheel 10. In this configuration, a force tooppose rotation of the wheel 10 is thus generated.

Even though the spring members 52 shown in FIG. 15 are coil springs,they need not necessarily be coil springs. They may be replaced by otherelastic bodies. The portion where the spring members (i.e. elasticbodies) are fitted of the holder 12 may be made, as shown in FIG. 9,smaller in width than the remaining portion of the holder 12 so as tomake efficient use of the elasticity of the spring members.

Fourteenth Embodiment

FIG. 16 is a diagram showing a fourteenth embodiment of the presentinvention. Referring to FIG. 16, the rigid external member 55 isdisposed outside the holder 12 with a piezoelectric element 60 disposedbetween the rigid external member 55 and the holder 12 on each side. Inother respects, the configuration of the present embodiment is the sameas that of the thirteenth embodiment of the present invention. When avoltage is applied to each of the piezoelectric elements 60, thickness pof each of the piezoelectric elements changes. For example, when avoltage is applied across each of the piezoelectric elements 60 causingthickness p of each of the piezoelectric elements 60 to increase, theholder 12 is pressed inwardly to brake the wheel 10.

Namely, applying a voltage across each of the piezoelectric elements 60generates a force to oppose rotation of the wheel 10, so that the wheel10 can perform scribing in a stable manner. According to the presentembodiment, the force to oppose rotation of the wheel 10 can becontrolled by controlling the voltage applied to the piezoelectricelements 60. This makes it easy to set conditions for scribing accordingto the condition of the mother substrate to be scribed.

Fifteenth Embodiment

In the first to fourteenth embodiments, the wheel 10 is not restrainedby the wheel pin 11 and is freely rotatable about the wheel pin 11. In afifteenth embodiment shown in FIG. 17 of the present invention, thewheel 10 and the wheel pin 11 are united. As shown in FIG. 17, the wheelpin 11 extends to outside the holder 12. The holder 12 has a support rod123 with a plate spring 41 disposed between the wheel pin 11 extendingto outside the holder 12 and the support rod 123.

A cylindrical member 111 is mounted on the portion outside the holder 12of the wheel pin 11. When the cylindrical member 111 is pressed by theplate spring 41, the cylindrical member 111 presses the wheel pin 11 tobrake rotation of the wheel pin 11. Since, in the present embodiment,the wheel pin 11 and the wheel 10 are united, braking the wheel pin 11brakes the wheel 10. A force to oppose rotation of the wheel 10 is thusgenerated so as to allow the wheel 10 to perform scribing in a stablemanner.

Sixteenth Embodiment

FIG. 18 is a diagram showing a sixteenth embodiment of the presentinvention. In this embodiment, too, the wheel 10 and the wheel pin 11are united. The configuration shown in FIG. 18 differs from that shownin FIG. 17 in that, instead of the plate spring 41, a piezoelectricelement 60 is disposed between the support rod 123 and the cylindricalmember 111 of the wheel 11. In other respects, the configuration shownin FIG. 18 is the same as that shown in FIG. 17.

In the configuration shown in FIG. 18, applying a voltage across thepiezoelectric element 60 brakes the cylindrical member 111 andeventually the wheel pin 11. Thus, a force to oppose rotation of thewheel 10 is generated in the configuration of the present embodimentwith the wheel pin 11 and the wheel 10 united. In the presentembodiment, the force to oppose rotation of the wheel 10 can be easilyadjusted by adjusting the voltage applied across the piezoelectricelement 60.

Seventeenth Embodiment

FIG. 19 is a diagram showing a seventeenth embodiment of the presentinvention. In this embodiment, too, the wheel 10 and the wheel pin 11are united. Referring to FIG. 19, an electromagnetic brake 61 isattached to the portion extending outside the holder 12 of the wheel pin11. The electromagnetic brake 61 is controlled by a control power supply62. The electromagnetic brake 61 may be, for example, something like amotor.

With the wheel 10 united with the wheel pin 11, a force generated by theelectromagnetic brake 61 to oppose rotation of the wheel 10 is directlyapplied to the wheel 10. Thus, in the present embodiment, the wheel 10is directly braked by the electromagnetic brake 61, so that the force tooppose rotation of the wheel 10 can be accurately controlled.

Eighteenth Embodiment

FIG. 20 is a drawing showing an eighteenth embodiment of the presentinvention. In this embodiment, too, the wheel 10 and the wheel pin 11are united. Referring to FIG. 20, a fluid brake 65 is attached to theportion extending outside the holder 12 of the wheel pin 11. The fluidbrake 65 is internally filled with a fluid 67 such as oil. The wheel pin11 extends, outside the holder 12, through the fluid brake 65. Theportion extending inside the fluid brake 65 of the wheel pin 11 has apropeller 65 or something like that so as to brake rotation of the wheelpin 11.

Thus, a force to oppose rotation of the wheel 10 united with the wheelpin 11 is generated by the fluid brake 65 and is applied to the wheel10, so that the wheel 10 can perform scribing in a stable manner.

Nineteenth Embodiment

FIG. 21 is a diagram showing a nineteen embodiment of the presentinvention. In this embodiment, the wheel 10 and the wheel pin 11 are notunited. In this embodiment, a magnetized holder 12 is used to press thewheel 10 against a side of the holder 12 to thereby generate a force tooppose rotation of the wheel 10.

The holder 12 formed of tool steel which is a magnetic material can bemagnetized. Referring to FIG. 21, the holder 12 serves as ahorseshoe-shaped magnet 20 with one end being a north pole and the otherend being a south pole. The wheel 10 and the wheel pin 11 are disposedbetween the north and south poles. The flux density between the northand south poles in FIG. 21 is 3 mT (millitesla), i.e. not lower than 30Gauss. This level of flux density is high enough to press the wheel 10against the holder 12. Thus, a force to oppose rotation of the wheel 10can be generated.

As described above, according to the present embodiment, the wheel 10can scribe glass in a stable manner without requiring any additionalpart to be provided for the holder 12.

1. A glass cutting machine for moving, on glass, a wheel having acutting edge on an outer circumference thereof while pressing the wheelagainst the glass causing the wheel to rotate and forming a fracturelayer on the glass; comprising a mechanism for opposing rotation of thewheel.
 2. A glass cutter having a wheel for forming a fracture layer onglass, a wheel pin supporting the wheel, and a holder supporting thewheel pin, wherein a mechanism for opposing rotation of the wheel duringthe wheel rotates is provided.
 3. The glass cutter according to claim 2,wherein the mechanism for opposing rotation of the wheel during thewheel rotates comprising: the holder being provided with a magnet, themagnet generating a magnetic flux forming a magnetic field to press thewheel against the holder.
 4. The glass cutter according to claim 2,wherein the mechanism for opposing rotation of the wheel during thewheel rotates comprising: wherein the holder includes a first part and asecond part with a magnet disposed therebetween, and wherein the magnetgenerates a magnetic flux forming a magnetic field to press the wheelagainst the holder.
 5. The glass cutter according to claim 2, whereinthe mechanism for opposing rotation of the wheel during the wheelrotates comprising: wherein the holder includes a first part and asecond part, wherein a magnet is held at least in a first portion of aregion between the first part and the second part, wherein a nonmagneticbody is held in a second portion, excluding the first portion, of theregion between the first part and the second part, and wherein themagnet generates a magnetic flux forming a magnetic field to press thewheel against the holder.
 6. The glass cutter according to claim 2,wherein the mechanism for opposing rotation of the wheel during thewheel rotates comprising: wherein the holder includes a first part and asecond part, wherein the first part includes a first magnet embeddedtherein and the second part includes a second magnet embedded therein,and wherein the first and second magnets generate a magnetic fluxforming a magnetic field to press the wheel against the holder.
 7. Theglass cutter according to claim 2, wherein the mechanism for opposingrotation of the wheel during the wheel rotates comprising: wherein theholder includes a top surface where the wheel is disposed, two inclinedsurfaces, and three mutually perpendicular flat surfaces, wherein afirst magnet is disposed on one of the two inclined surfaces of theholder and a second magnet is disposed on the other of the two inclinedsurfaces of the holder, and wherein the first and second magnetsgenerate a magnetic flux forming a magnetic field to press the wheelagainst the holder.
 8. The glass cutter according to claim 2, whereinthe mechanism for opposing rotation of the wheel during the wheelrotates comprising: wherein the holder includes a first part and asecond part, wherein the first and second parts are wound with a coil,and wherein the coil generates a magnetic flux forming a magnetic fieldto press the wheel against the holder.
 9. The glass cutter according toclaim 2, wherein the mechanism for opposing rotation of the wheel duringthe wheel rotates comprising: wherein a fabric member is disposed in theholder, the fabric member being in contact with the wheel so as tooppose rotation of the wheel.
 10. The glass cutter according to claim 2,wherein the mechanism for opposing rotation of the wheel during thewheel rotates comprising: wherein a spring member is disposed in theholder, the spring member being in contact with the wheel so as tooppose rotation of the wheel.
 11. The glass cutter according to claim 2,wherein the mechanism for opposing rotation of the wheel during thewheel rotates comprising: wherein a washer is disposed between theholder and the wheel, the washer being in contact with both the holderand the wheel.
 12. The glass cutter according to claim 2, wherein themechanism for opposing rotation of the wheel during the wheel rotatescomprising: wherein the holder includes a first part and a second part,wherein the first part and the second part are united, with an elasticspacer interposed therebetween, by being clamped with a clamping screw,and wherein the wheel and the holder generate, by being clamped by theclamping screw, a prescribed friction resistance.
 13. The glass cutteraccording to claim 2, wherein the mechanism for opposing rotation of thewheel during the wheel rotates comprising: wherein a spring member isdisposed between the holder and the external rigid member, elasticity ofthe spring member causing the holder to be pressed against the wheel.14. The glass cutter according to claim 2, wherein the mechanism foropposing rotation of the wheel during the wheel rotates comprising:wherein a piezoelectric element is disposed between the holder and theexternal rigid member, and the holder is caused to be pressed againstthe wheel by controlling a voltage applied across the piezoelectricelement.
 15. The glass cutter according to claim 2, wherein themechanism for opposing rotation of the wheel during the wheel rotatescomprising: wherein the wheel and the wheel pin are united, wherein thewheel pin extends to outside the holder, and wherein the wheel pin issubjected to a force to oppose rotation thereof generated by a springmember attached to the holder.
 16. The glass cutter according to claim2, wherein the mechanism for opposing rotation of the wheel during thewheel rotates comprising: wherein the wheel and the wheel pin areunited, wherein the wheel pin extends to outside the holder, and whereinthe wheel pin is subjected to a force to oppose rotation thereofgenerated by a piezoelectric element attached to the holder.
 17. Theglass cutter according to claim 2, wherein the mechanism for opposingrotation of the wheel during the wheel rotates comprising: wherein thewheel and the wheel pin are united, wherein the wheel pin extends tooutside the holder, and wherein the wheel pin is subjected to a force tooppose rotation thereof generated by an electromagnetic brake attachedto the holder.
 18. The glass cutter according to claim 2, wherein themechanism for opposing rotation of the wheel during the wheel rotatescomprising: wherein the wheel and the wheel pin are united, wherein thewheel pin extends to outside the holder, and wherein the wheel pin issubjected to a force to oppose rotation thereof generated by a fluidbrake attached to the holder.
 19. The glass cutter according to claim 2,wherein the mechanism for opposing rotation of the wheel during thewheel rotates comprising: wherein the holder is magnetized, themagnetized holder generating a magnetic flux forming a magnetic field topress the wheel against the holder.
 20. A glass cutting method formoving, on glass, a wheel having a cutting edge on an outercircumference thereof while pressing the wheel against the glass causingthe wheel to rotate and forming a fracture layer on the glass, whereinglass is cut by forming a scribe line thereon using, when the wheelrotates, means for opposing the rotation of the wheel.